Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
755 PM EDT Sat Apr 13 2024

Valid 12Z Wed Apr 17 2024 - 12Z Sun Apr 21 2024

...Synoptic Overview, Guidance Evaluation, & Preferences...

An upper level ridge axis is expected to be in place across the
eastern mainland and into the Yukon Territory and southeast
panhandle region for the middle of the week.  Meanwhile, a storm
system over the North Pacific tracks in the general direction of
the AK Peninsula by late Wednesday before stalling, and then
slowly moving back to the south over the central Gulf.  This
brings a return to more rain and snow for southern coastal areas
of the state, particularly from the AK Peninsula to Kodiak Island.
 Meanwhile, a second low pressure system is forecast to track
across the Bering and weaken with time through midweek, and some
of the shortwave energy from this may interact with the low moving
north across the western Gulf. 

The 12Z model guidance suite features decent overall synoptic
scale agreement across the Alaska domain for the beginning of the
forecast period Wednesday.  Upon examination of the ML guidance
from the ECMWF, there is more support for the faster northward
track of the low towards Kodiak Island by 12Z Wednesday, which is
also closer to the 12Z GFS position.  The CMC depicts a solution
with the low south of the model consensus over the Gulf, but an
overall improvement compared to recent days.  The fronts/pressures
forecast was based on a multi-model blend as a starting point
through Thursday with more weighting towards the GFS given its
solution more in line with the ML guidance, and then increasing
percentages of the GEFS and EC means going into next weekend.


...Weather/Hazards Highlights...

Coastal rain and mountain snow is likely to increase going into
the Wednesday-Thursday time period from Kodiak Island to the
Prince William Sound region as moist onshore flow increases ahead
of the Pacific low moving towards the coast.  Similar to
yesterday, there has been a slight westward trend with the highest
QPF from this event, with the highest totals near Kodiak Island
and the eastern AK Peninsula.  Strong onshore flow over this
region is expected to produce high waves and gusty winds over 40
mph at times, especially through coastal inlets.  Light showers
are possible farther inland across southern mainland Alaska. 
Temperatures are generally expected to be mild with readings in
the mid 40s to mid 50s for highs across most Interior locations,
and generally 40-45 degrees near the southern coastal areas.  A
cooling trend is likely by next weekend as the upper ridge axis
breaks down.  The Brooks Range will be the demarcation for much
colder conditions across the North Slope and extending to the
Arctic Coast, with highs struggling to reach the freezing mark
closer to the Arctic Coast. 

Hamrick


Additional 3-7 Day Hazard Information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can also be
found at:
https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml
https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html